Great Britain: Victoria Proof Pattern "Palladium-Hydrogenium" 1/2 Sovereign 1869 PR63 Cameo NGC,...

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Victoria Proof Pattern "Palladium-Hydrogenium" 1/2 Sovereign 1869 PR63 Cameo NGC, KM-Unl, S-Unl, W&R-Unl, cf. Coincraft VPT-455 (reeded edge). Plain Edge. Obv. Young head of Victoria left. Rev. PALLADIUM - HYDROGENIUM * 1869 * around GRAHAM. A rare and curious Pattern designed by Thomas Graham, master of the Royal Mint from 1855 until his death in 1869, but also an eminent chemist, renowned for his pioneering work on dialysis and the diffusion of gases (Graham's Law). His interest in metallurgy prompted the striking of coins in various metals and establishing their reaction to gases. He discovered in 1866 that palladium could absorb multiples of its own volume of hydrogen, making it a harder and less ductile metal. He called this new alloy palladium-hydrogenium, as noted on the reverse of this coin, which also includes his name. Very few of these test pieces are known to exist, though we do know there was an example in the King Farouk collection. A fascinating numismatic curiosity that should delight collectors of such items.

Ex. Sincona British Collection (Part II, May 2022, Lot 347)

Metal: Palladium
Diameter: 19mm

More information about Great Britain Coins. See also: Great Britain World Coin Nationality.

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